When I was 17 or 18, I got a 239 Ford that had been sitting out in a guy's backyard with a tin can over the carburetor for heaven knows how many years.

Fresh plugs, fresh points, kit in the carb. Ran like a Swiss watch.

I suspect this was only because of my ignorance - had I known better, it probably wouldn't have ran at all...

Fast forward 3 decades. Bought a 2002 Sportster engine with 3000 miles on it; pulled from a wrecked bike. went to put cams in it, check the crank run out while the cam chest was open and found almost .006" TIR on the pinion shaft. Tearing the motor apart so I could split the cases and true the crank, found one of the cylinders had got condensation in it.

Basically, if I had tried to run that motor as it was, I wouldn't have got much life out of it.

Like previous postershave pointed out, a gasket set is not terribly expensive. If the motor gets torn down, and everything is just fine, then it goes together with nothing more than the gasket kit.

If there's issues, probably not going to get any cheaper to fix by running it